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Actively exploited

CVE-2021-36742 Trend Micro Multiple Products Improper Input Validation Vulnerability

Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security contain an improper input validation vulnerability that allows for privilege escalation.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch urgentlyCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 3 Nov 2021.
  • Rated High severity (CVSS 7.8, scored by CISA).
  • It has been in the catalogue for 1,829 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

A improper input validation vulnerability in Trend Micro Apex One, Apex One as a Service, OfficeScan XG and Worry-Free Business Security 10.0 SP1 allows a local attacker to escalate privileges on affected installations. Please note: an attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

Affected Versions

ProductVersions
Trend Micro Trend Micro Apex One2019, SaaS
Trend Micro Trend Micro OfficeScanXG SP1
Trend Micro Trend Micro Worry-Free Business Security10.0 SP1

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply updates per vendor instructions.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated high, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 17 Nov 2021 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

More Exploited Trend Micro Flaws

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CVE-2026-34926Trend Micro Apex One (On-Premise) Directory Traversal VulnerabilityAdded 21 May 2026CVE-2025-54948Trend Micro Apex One OS Command Injection VulnerabilityAdded 18 Aug 2025CVE-2023-41179Trend Micro Apex One and Worry-Free Business Security Remote Code Execution VulnerabilityAdded 21 Sep 2023CVE-2022-40139Trend Micro Apex One and Apex One as a Service Improper Validation VulnerabilityAdded 15 Sep 2022CVE-2022-26871Trend Micro Apex Central Arbitrary File Upload VulnerabilityAdded 31 Mar 2022CVE-2019-18187Trend Micro OfficeScan Directory Traversal VulnerabilityAdded 3 Nov 2021

All 12 exploited Trend Micro vulnerabilities

Not Sure If You Are Exposed?

Our attack surface and vulnerability teams can check your internet-facing estate for CVE-2021-36742 and every other exploited flaw on the list.

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2021-36742
  3. CVE record: CVE-2021-36742
  4. FIRST EPSS
  5. success.trendmicro.com/dcx/s/solution/000287819?language=en_US, https://success.trendmicro.com/dcx/s
  6. success.trendmicro.com/solution/000287819
  7. success.trendmicro.com/solution/000287820
  8. success.trendmicro.com/jp/solution/000287796
  9. success.trendmicro.com/jp/solution/000287815